The objectives of the proposed work are: to perform clinical evaluation of terminal deoxynucleotidyl transferase for the differential diagnosis of leukemias and to develop an immunofluorescent test for this enzyme which may be of clinical value for the diagnosis and follow-up of certain leukemias. BIBLIOGRAPHIC REFERENCES: Srivastava, B.I.S. Deoxynucleotide-polymerizing Enzyme Activities in T- and B-Cells of Acute Lymphoblastic Leukemia Origin. Cancer Res. 36: 1825-1830, 1976. Srivastava, B.I.S., Khan, S.A. and Henderson, E.S. High Terminal Deoxynucleotidyl Transferase Activity in Acute Myelogenous Leukemia. Cancer Res. 36: 3847-3850, 1976.